Registering devices to Pexip Infinity

Pexip Infinity acts as a SIP registrar and H.323 gatekeeper.

In addition to SIP and H.323 endpoints, Infinity Connect desktop clients and Infinity Connect Mobile clients for Android can also register to Pexip Infinity Conferencing Nodes. This allows Pexip Infinity to route outbound calls to those registered devices without having to go via a SIP proxy or rely on DNS.

Note that devices do not need to be registered in order to make inbound calls to Pexip Infinity.

For end-user instructions on how to register a device, see Registering your device to receive calls.

Configuration summary for enabling registrations

To configure Pexip Infinity to accept registrations and route calls to registered devices you must:

1. Ensure that the Pexip Infinity's registrar service is enabled (Service configuration > Registrar).
2. Configure the aliases that devices are allowed to register to Pexip Infinity (Service configuration > Device aliases).
3. If you want to allow point-to-point calls to be made to a registered device, configure appropriate Gateway Routing Rules (Service configuration > Distributed Gateway).

Each of these steps plus is described in more detail below, after the explanation of how Pexip Infinity manages registered devices.

How it works

Registering devices

The registrar service on Pexip Infinity is enabled by default. However, a device can only register to Pexip Infinity if the alias it wants to register has been added to Pexip Infinity's list of allowed device aliases (Service configuration > Device aliases).

Device registrations can optionally also be subject to authentication. To enforce authentication, username and password credentials must be included when the alias is added to Pexip Infinity's list of allowed device aliases. When credentials have been included, the device's registration request will be challenged and the device will only be allowed to register with that alias if it provides matching credentials. Pexip Infinity supports Digest authentication only.

A device can register to any Conferencing Node. Pexip Infinity does not apply any form of registration load balancing or failover. Multiple devices can register with the same alias.

• To register a SIP device, enter the IP address or FQDN of a local Conferencing Node as the SIP proxy.

• To register an H.323 device, enter the IP address or FQDN of a local Conferencing Node as the H.323 gatekeeper.

  All of the device aliases presented in the H.323 registration request must be in the list of allowed device aliases. If any alias is not present, none of the aliases will be allowed to register. Additionally, if device authentication is being used, all of the aliases presented in the request must use the same credentials.

• If your endpoint supports SIP and H.323, you should register it to Pexip Infinity over just one protocol, either SIP or H.323, but not both.
• To register an Infinity Connect client, enter either the IP address or FQDN of a local Conferencing Node, or the IP address or FQDN of the reverse proxy, as the registration server address. Infinity Connect clients register over the WebRTC protocol.

After the device has registered it must periodically refresh that registration.

Calling registered devices

Whenever Pexip Infinity needs to place an outbound call (such as when adding a participant to a conference, or when a Gateway Routing Rule has been matched), it will first look through the set of devices currently registered to any of the Conferencing Nodes on the Pexip Infinity platform. If the alias it is trying to call is currently registered, then the Conferencing Node to which the device is registered will place the call to the device. (Media may flow through other nodes, as per the platform's standard distributed conferencing behavior.)

The outbound call is always placed to the registered device over the same protocol that it used to make the registration.

If multiple devices are registered with the same alias, Pexip Infinity will place a call to each device, i.e. it will fork the call.

If the device alias is not registered, Pexip Infinity will still attempt to place a call to that alias in its standard manner — routing the call via other means such as DNS or a SIP proxy.

Note that if you want to allow point-to-point calls to be made to a registered device via the Pexip Distributed Gateway, then, as is the case for all gateway calls, an appropriate Gateway Routing Rule must be configured (Service configuration > Distributed Gateway). The rules should have a Destination alias that matches the registered alias, and the Outgoing location set to Automatic.

Avoiding call looping

Gateway Routing Rules that are intended to route calls to devices registered to Pexip Infinity (e.g. Infinity Connect clients) could, depending upon DNS configuration, result in call looping if the destination device alias is not currently registered. This occurs because the Pexip Distributed Gateway, on not finding the registered alias, will attempt to place the call via DNS or a call control system. This could result in the call being routed back to Pexip Infinity which would then match the same Gateway Routing Rule and result in a loop.

To work around this issue, we recommend:

1. Configure a SIP proxy (Call control > SIP proxies) and name it something like "Null destination (reject calls)".
2. Set the proxy's address to nowhere.invalid (the .invalid suffix is guaranteed not to resolve as defined in RFC 2606) — the port/protocol is irrelevant.
3. Ensure that the gateway rule (Service configuration > Distributed Gateway) that has been set up to match the registered clients has an appropriate priority, so that no generic/wildcard gateway rules match prior to this more specific rule.
4. Set the rule's Protocol to SIP (this is the outbound protocol where calls should be sent).
5. Set the rule's SIP proxy to the new "Null destination (reject calls)" proxy.

This now means that if the device is registered, Pexip Infinity will route the call to the device as usual, but if the device is not registered, the call will be routed to a proxy that does not exist and will fail cleanly and not loop.

Call routing logic

The stage in Pexip Infinity's call routing logic where it checks if a device is registered is shown in the following diagram:

Configuring the registrar service

Devices can only register to Pexip Infinity if the registrar service is enabled.

To configure Pexip Infinity's registrar service, go to Service configuration > Registrar. The options are:

Option	Description
Enable registrar	Controls whether devices can register to Pexip Infinity. Devices must register with a permitted alias (configured via Service configuration > Device aliases). The registrar service is enabled by default.
Minimum refresh delay	The minimum delay in seconds before a device's registration is refreshed. Default: 60 seconds.
Maximum refresh delay	The maximum delay in seconds before a device's registration is refreshed. Default: 90 seconds.

Specifying which aliases devices are allowed to register with

Devices can only register to Pexip Infinity with a permitted alias.

To configure the aliases that devices are allowed to register to Pexip Infinity, go to Service configuration > Device aliases. The options are:

Option	Description
Device alias	The alias URI with which the device must register to Pexip Infinity. The alias must be an exact match; regular expressions are not supported.
Service tag	This optional field allows you to assign a unique identifier to this service, which you can then use to track use of the service. For more information, see Tracking usage with a service tag.
Description	An optional description of the device.
Username and Password	The username and password credentials with which to authenticate the device. The credentials are optional and the device is not challenged if no credentials are entered. The username and password are case-sensitive.

Troubleshooting and logging

To see a list of all device aliases that are currently registered to the Pexip Infinity platform, go to Status > Registrations.

Successful registration requests and expired registrations are recorded in the administrator log.

Failed registration requests (due to, for example, an unknown device alias or authorization failure) and refreshed registrations are recorded in the support log only.

If a gateway call fails to be placed to a registered device, check that an appropriate Gateway Routing Rule has been configured that has suitable destination alias matching strings for the registered alias (and ensure that call looping cannot occur).